YT Industries has a new version of its Jeffsy trail bike out, and like Specialized, Trek, Giant, Merida and plenty more before it you now get downtube storage so there’s somewhere to stash your lunch. 

Accessed through a hatch inside the front triangle, the glovebox is undoubtedly a useful addition to any bike, but it takes more than that to make the Jeffsy a contender for best trail bike on the market today. 

Fortunately for YT then, there’s plenty more going on here with the third generation Jeffsy, starting with a change of travel.

Need to know

• New range runs from £5,999 for the YT Jeffsy Core 5, to £2,499 for the Core 1
• (read our review of the YT Jeffsy Core 5)
• Three frame materials, Ultra Modulus carbon, High Modulus carbon, and aluminium
• Travel paired back a smidge to 145mm from 150mm, fork remains at 150mm
• RockShox drivetrain throughout the range, from T-type AXS down to to NX 12speed
• Internal storage in the downtube, with two waterproof tool wraps ensconced inside
• Tweaked suspension characteristics, with more anti-squat and progression
• Geometry adjust via a flip chip, altering the BB height by 8mm and the head tube angle 0.6º

YT Jeffsy details

The fork remains at 150mm, but YT has chopped the bike’s travel down by 5mm to 145mm. Not much of a change, but the idea is to put the bike squarely between the downcountry Izzo (130mm) and the Capra enduro bike (165-170mm). 

YT is sticking with 29in wheels for the Jeffsy, which makes total sense to us for trail bike because the big hoops roll faster on pedally terrain and are unlikely to take the kind of beating enduro bikes would put them through.

What is big on YT’s agenda is to make the Jeffsy pedal better than the old bike. Long-time readers of mbr might remember that the Jeffsy Core 2 we reviewed two years back had great suspension but floundered on the climbs. All the new bikes now get size-specific effective seat tube angles. This means the position of the saddle relative to the bottom bracket will remain the same, even as the bike grows, putting riders of all sizes in the best position for pedalling. 

It’s not just the seat tube angle that’s been adjusted here either, YT has also increased the anti-squat to around 105% at 30% sag, meaning it should have more support when you’re pedalling, braking or pumping at the top of the travel. Simultaneously, YT has also gone after the other end of the stroke, adding in progression and support here too.

The carbon frame itself now comes in two different variants, an idea Santa Cruz pioneered with its C and premium CC carbon. For the Jeffsy there’s now a premium Ultra Modulus version only available on the Core 5, which YT says weighs slightly less (although there were no figures available for us). And a High Modulus, or slightly heaver version of carbon, on the Core 4 bike. Both have the same strength and fatigue resistance, YT says. 

Internal frame storage

What self-respecting carbon fibre bike would be complete without in-frame storage? Great rivals Canyon might well have the tech on its next mountain bike too, if our guesswork is on point, but YT’s managed to get in there first. The Jeffsy now has frame storage across all carbon models, and inside the compartment has been split in two, with neoprene frame bags supplied to take your gear. The door’s waterproof, as are those zippered bags too.

The range

YT Jeffsy Core 5 CF £5,999

14.8kg (size small)

Ultra Modulus carbon fibre frame with downtube storage 

SRAM XO NT AXS 12speed drivetrain

Fox 36 Factory fork

Fox Float X Factory shock

SRAM Code RSC brakes with HS2 rotors

YT Postman V2 dropper post

Renthal Apex stem and Renthal Fatbar alloy bar

Crankbrothers EN 3 AL wheelset, Maxxis Minion DHF/DHR II tyres with new EXO+ carcass and MaxxTerra compound 

 

YT Jeffsy Core 4 CF £4,999

15.1kg

High Modulus carbon fibre frame with downtube storage 

SRAM GX NT AXS 12speed drivetrain

RockShox Lyrik Ultimate fork

RockShox SDLX Ultimate shock

SRAM CODE RSC brakes

YT Postman V2 dropper post

Renthal APEX BLACK stem and YT alloy bar 

Crankbrothers EN 2 AL wheelset, Maxxis Minion DHF/DHR II tyres with new EXO+ carcass and MaxxTerra compound 

 

YT Jeffsy Core 3 CF £3,999

Carbon frame, 14.9kg

SRAM GX Eagle 12speed drivetrain

FOX 36 Performance fork

FOX Float X Performance shock

SRAM CODE R brakes

YT Postman V2 dropper post

Renthal stem and YT bar 

DT Swiss M1900 wheelset, Maxxis Minion DHF/DHR II tyres with new EXO+

 

YT Jeffsy Core 2 AL £2,999

Alloy frame, 15.5kg

SRAM GX Eagle 12speed drivetrain

FOX 36 Performance fork

FOX Float X Performance shock

SRAM CODE R brakes

YT Postman V2 dropper post

Renthal OE stem and bar

DT Swiss M1900 wheelset, Maxxis Minion DHF/DHR II tyres with new EXO+

 

YT Jeffsy Core 1 AL £2,499

Alloy frame, 16.0kg

SRAM SX/NX Eagle 12speed drivetrain

RockShox Lyrik Base fork

RockShox Deluxe SEL+ shock

SRAM DB8 brakes

YT Postman V2 dropper post

E13 BASE SUNRINGLE 329 wheelset, Maxxis Minion DHF/DHR II tyres with new EXO+

 

Geometry (as measured in the Low setting, in Size Large)

Head angle 64.1º

Seat angle 71.0º

Effective SA (@760mm) 78.2º

BB height 342mm

Chainstay 438mm

Front centre 803mm

Wheelbase 1241mm

Down tube 742mm

Seat tube 430mm

Top tube 600mm

Reach 477mm